The present application relates generally to a cooling system on a turbomachine; and more particularly to, a system for and method of regulating a cooling fluid within a turbomachine.
In some turbomachines, such as gas turbines, a portion of the air compressed by the compressor is typically diverted from combustion to cool various stationary and rotating components or to purge cavities within a gas turbine. The diverted airflow (hereinafter “cooling fluid”, or the like) consumes a considerable amount of the total airflow compressed by the compressor. The diverted cooling fluid is not combusted, and thus reduces the performance of the gas turbine. Regulating and controlling the cooling fluid can dramatically increase the performance of the turbine.
Typically, the cooling fluid is extracted from the compressor, bypasses the combustion system, and flows through a cooling circuit. The cooling circuit may run adjacent various turbine components including the turbine wheelspace areas. The cooling circuit is typically integrated with a seal system.
Relatively tight clearances may exist between the seal system components and the gas turbine rotor. Seal system wear may enlarge the seal system clearances. This wearing allows excess cooling fluid to flow downstream of the seal system; which reduces the overall efficiency of the gas turbine. The wear may be caused by a “trip” (an emergency shutdown of the turbomachine). Seals may also wear over time from gas turbine operation.
Some cooling circuits may include a plurality of internal chambers that direct the cooling fluid to a specific wheelspace area. Moreover, each of the internal chambers may include a plug, which prevents the cooling fluid from flowing into a specific wheelspace area. As the seal system wears the plugs may be removed or repositioned to reduce the cooling fluid flow downstream of the seals.
There are a few possible problems with the currently known cooling circuits. The unpredictable nature of the seal system wear does not allow for a deterministic flow of the cooling fluid through the cooling circuit. This typically leads to the general practice of over sizing the flow area within the cooling circuit; thereby allowing for excessive cooling fluid to flow and thus reducing the overall efficiency of the gas turbine. Gas turbines that incorporate plugs must be shutdown and disassembled before each plug may be removed or repositioned. The currently known systems may not allow for controlling the cooling fluid, while the gas turbine is in operation.
For the foregoing reasons, there is a need for a system that allows for regulating the cooling fluid passing into at least one wheelspace area of a gas turbine, while the gas turbine is in operation. The system should ensure adequate cooling of the at least one wheelspace area while improving the efficiency of the gas turbine. The system should also provide for a deterministic flow through the cooling circuit.